The production and transport of hydrogen for field applications remains a logistical problem. The low energy density of hydrogen necessitates larger containers for storage and transport relative to those for hydrocarbon fuel. Even with high pressurization of 10,000 pounds per square inch or metal hydride storage, a relatively large container is required to hold an energy equivalent of hydrogen. As a result, the use of hydrogen to operate a quiet and environmentally benign electricity generator in the field necessitates on site generation of hydrogen.
The term “reformation” is used in the petroleum refining industry to refer to catalytic conversion of lower octane naphtha to higher octane naphtha with the production of hydrogen co-product. The term “reformation” is used herein to describe reaction of a hydrocarbon fuel stock, liquid at standard temperature and pressure (STP), to form hydrogen and carbon monoxide, referred to as synthesis gas or syngas. Unfortunately, existing technologies for fuel reformation to syngas have met with limited acceptance. For example, the invention of U.S. Pat. No. 6,221,280 requires an anhydrous environment, air as an oxidant and a fuel reformation temperature of greater than 1050° Celsius.
Another impediment to reformation of fuel to syngas is catalyst intolerance to sulfur. These catalysts contain transition metals that form sulfides on exposure to sulfur at elevated reformation temperatures. The sulfided catalyst is catalytically inactive, referred to as poisoned.
Attempts to catalytically reform sulfur-containing hydrocarbon fuels have included sulfur removal from the hydrocarbon fuel prior to exposure to the reformation catalyst as described in U.S. Pat. No. 5,270,272 and sulfur-tolerant catalyst as described in U.S. Pat. No. 6,238,816 and U.S. Pat. No. 6,967,063. Unfortunately, hydrocarbon fuel desulfurization prior to fuel reformation adds processing steps and has proven only incrementally successful. Sulfur-tolerant catalysts usually require large amounts of water as an oxidant, adding a containment and transport burden. These catalysts may also demonstrate low syngas yields. All of these are significant impediments for the military to use sulfur-containing fuels for field generation of electricity.
There is a need for a catalyst to directly convert sulfur-containing hydrocarbon fuels to synthesis gas at temperatures in the range of 800 to 1000° Celsius.